ES2688431T3 - Procedure and installation for the production of sulfuric acid - Google Patents

Abstract

A process for the production of sulfuric acid, comprising the steps of: (i) feeding liquid acid with a first concentration to a gas purification in the form of a packed-bed absorber or a packed-bed drying tower; (ii) passing a gas through the gas purification so that a second concentration of the liquid acid is reached; (iii) withdrawing the liquid acid from the gas purification collector, wherein the gas purification collector is divided by a dividing wall into a first and a second section, characterized by adjusting the concentration of the liquid acid collected in the first section at the first concentration, the liquid acid with the first concentration is fed back at least partially from the first section to step (i), and the liquid acid with the second concentration collected in the second section, and the concentration of the liquid acid in the first section is adjusted with acid or water.

Description

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DESCRIPTION

Procedure and installation for the production of sulfuric acid

The present invention relates to a process for the production of sulfuric acid or oleum, as well as to facilities for carrying out these processes.

Pure sulfuric acid (H2SO4) is a colorless, translucent, corrosive and hygroscopic liquid, with an oil-like consistency. It is one of the most important basic chemical products and is used in various technical sectors, including in the production of fertilizers, to produce other mineral acids, as an oxidizing agent and as a solvent for many minerals. The concentration of commercially available liquid H2SO4 varies with the intended use; The usual concentrations are in the range of 35% by weight of H2SO4 (battery acid), 75% by weight of H2SO4 and 100% by weight of H2SO4.

Smoking sulfuric acid (oleum, H2S2O7) is a solution of sulfur trioxide (SO3) in sulfuric acid. It is used, inter alia, as an intermediate for the transport of sulfuric acid and compounds containing sulfuric acid, as a reactive agent in organic chemistry and in the manufacture of explosives. The concentration of SO3 in the commercially available oil varies with the intended use; The usual concentrations are in the range of 25% by weight of SO3, 30-35% by weight of SO3 and 65% by weight of SO3.

Various methods for preparing sulfuric acid or oleic acid are known, such as the lead chamber and vitriol process. Due to various inconveniences of the processes, sulfuric acid or oleum is produced almost exclusively by the so-called "contact" process. For oil, this procedure is described, for example, by Douglas K. Louie, "Handbook of Sulfuric Acid Manufacturing", 2nd edition, DKL Engineering, Inc., Richmond Hill, Ontario, Canada, 2008, page 19-7.

The contact process is characterized, among other things, by sending liquid sulfuric acid or liquid oleum of a certain concentration to an absorber, where contact with a gas containing SO3 occurs and an increase in the concentration of said sulfuric acid or oleic acid. In the case of sulfuric acid, an exothermic reaction of SO3 with the water fixed by sulfuric acid will occur, according to the reaction equation:

SO3 + H2O ^ H2SO4

In the case of oleum, an exothermic reaction of sulfuric acid with SO3 occurs according to the reaction equation:

SO3 + H2SO4 ^ H2S2O7

Typically, after the absorption of SO3 the concentrated acid / oleic acid is taken and diluted sufficiently so that one part of the acid / oleum can be recirculated towards the absorber while the other part is extracted as the final product.

The necessary SO3 can be produced by the reaction of SO2 on a V2O5 catalyst, which is normally favored with K2SO4. SO2 can be obtained by combustion of elemental sulfur in dry gas containing oxygen, for example dry air.

To generate the amount of dry gas with oxygen content required for the combustion of elemental sulfur, the hygroscopic properties of sulfuric acid can be exploited. However, in principle other hygroscopic liquid acids can be used, for example phosphoric acid. The gas containing water is driven into a drying tower, where the humidity of said gas is absorbed by the acid. As a consequence of this absorption, the concentration of the acid inside the drying tower will decrease. However, to ensure sufficient drying, the concentration of sulfuric acid must be maintained at a certain minimum concentration.

This raises the problem that, in some applications, the desired sulfuric acid / oleic acid concentration in the final product is different from that required for the reaction in the absorber or for the removal of water in the drying tower, so that uniform dilution or concentration and subsequent division of the product formed in the absorber or in the drying tower as described above is possible. For example, the sulfuric acid that is fed to the absorber has a concentration of approximately 98.5% by weight and the sulfuric acid removed from the absorber typically has a concentration of approximately 99.4% by weight, while the desired concentration in the product final is in some cases around 99.1 - 99.2% by weight. Also, the sulfuric acid that is fed to the drying tower may have to have a concentration greater than about 94% by weight, while the desired concentration in the final product may be approximately 93% by weight.

In the prior art, this problem has been solved so far, for example, by using a separate absorber or a separate drying tower to prepare sulfuric acid / oleum of the desired concentration. This is technically complicated and implies additional costs in terms of energy and materials use.

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US 3,172,725 describes a process according to the preamble of claim 1, and is directed to a process for producing concentrated sulfuric acid from gaseous streams containing from 1% to 7% sulfur dioxide. In this case, the gas stream is cleaned, enriched and converted into SO3. The SO3 gas stream comes into contact with a liquid phase and sulfur trioxide is absorbed from the gas phase into the liquid solution. Some haze or droplets of sulfuric acid can be entrained in the gas phase, which then passes through a drag separator bath, over a dike, and through a less concentrated solution of acid that is typically maintained at an acid concentration of approximately 63%. Thus a substantially complete removal of sulfur trioxide from the gas phase takes place.

EP 0 151 010 A2 provides a process for producing concentrated sulfuric acid from a hot gaseous stream comprising water and sulfuric trioxide. Sulfuric acid is provided through distributor systems. The acid is collected in a manifold divided by a wall lined with antacid brick, by which a collection zone is separated from an absorption zone. A recirculation system starts from the collection area, through which portions of the acid can also be extracted through a pipe. In addition, portions of the acid from the absorption zone are recirculated to the distributors.

Document DE 1 667 692 A1 teaches a process for regenerating spent sulfuric acid, used in an alkylation process. Alkylation takes place in several chambers of a reactor. Contaminated acid is contacted with steam during alkylation, to obtain a diluted acid, from which can be separated into a decanter contained diluents. After this, the purified diluted acid is fed to two evaporation zones to adjust a concentration of 97.5% by weight before recycling.

Document DE 34 10 109 A teaches a wash column for the desulfurization of gases, with two washing zones each having a plurality of spaced nozzle assemblies for washing the gas with a respective washing liquid containing additives that They fix sulfur compounds. At the bottom of the washer, the liquid discharged from the nozzles and containing sulfur compounds reaches a collector to which limestone is added. Each of the washing areas is provided with a separate circulation system for the washing liquid.

The object of the present invention is to provide a method and a system that overcomes the drawbacks of the prior art described above and, in particular, to obtain a uniform concentration of acid with lower costs in terms of energy and use. of materials.

This technical problem is solved by a process and an installation to produce sulfuric acid according to claims 1 and 6, respectively.

Preferred embodiments of the invention follow from the dependent claims.

By separating the gas purification manifold into two sections, it is possible to remove the acid product from one section and use the acid collected as circulating acid in the other section. A separate pumping tank is not required for circulating acid.

Preferably, the concentration adjustment is already carried out within the gas purification manifold, thus avoiding a separate collection tank.

More preferably, the concentration is adjusted with water, for example deionized water. However, it is also possible to use acid to adjust the concentration, for example, a cross-flow of acid from a drying tower.

In a preferred option of the invention, the level of liquid in the two sections of the manifold is controlled, so that no mixing occurs between the liquids of both sections.

Alternatively, it is possible to have a liquid overflow from the second section, the acid concentration being different compared to the acid concentration in the first section.

In a particularly preferred embodiment, the second section, from which the product acid is removed, is designed such that the volume of descending liquid entering the second section is greater than the amount of product acid removed from the gas purification, so that there is always an overflow towards the first section, from which circulating acid is taken.

The gas can be passed through the purification of gas both in parallel stream flow and in countercurrent flow relative to the descending acid. The countercurrent version is preferred, since a greater concentration gradient is obtained along the height of the tower, which results in a more effective adjustment of the acid concentration with the gas.

Preferably, the gas comprises SO3. More preferably, in step (ii) the gas containing SO3 has a volume fraction of at least 5 to 35% by weight of SO3. Other possible components are sulfur dioxide (SO2), oxygen (O2), nitrogen (N2), carbon dioxide (CO2) and some other minor components.

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In another embodiment, the gas may comprise sulfur dioxide (SO2). Preferably, the exhaust gas containing sulfur dioxide, from the overall process for the production of liquid acid, can be recycled to the gas purification. In this way the global emission of sulfur dioxide can be reduced.

The process of the invention can be carried out mainly with, and producing, sulfuric or oleic acid of any concentration.

For sulfuric acid (H2SO4), the second concentration of H2SO4 is preferably at least 93% by weight, more preferably at least 99% by weight. It is further preferred that the concentration of H2SO4 in step (i) be 98-99% by weight.

For the oil (H2S2O7), the second concentration of free sulfur trioxide (SO3) is preferably at least 20% by weight, more preferably at least 40% by weight, while the maximum attainable concentration of free SO3 depends on both the concentration of SO3 in the gas of step (ii) as of the temperature of the liquid or, more specifically, of the partial pressure of SO3 on the oil, which depends on the temperature.

It is further preferred that the concentration of free SO3 in step (i) be approximately 1-2% by weight greater than the preferred minimum concentration of SO3. A typical minimum concentration is 33-40% by weight, and a concentration of 36% by weight is preferred.

In a preferred embodiment, the gas purification is an absorber, preferably an absorber of a sulfuric acid plant. The process for the production of sulfuric acid with a certain minimum concentration comprises the steps of:

(i) feed a liquid acid absorber tower with a concentration that is less than the minimum concentration;

(ii) passing a gas containing sulfur trioxide (SO3) through the absorber tower so that the sulfur trioxide is absorbed at least partially in the liquid acid to increase the concentration of the liquid acid to at least the concentration minimum

(iii) remove the acid from the absorber manifold,

wherein the absorber manifold is divided by a dividing wall into a first and a second section, where the liquid acid collected in the first section is diluted to a concentration that is lower than the minimum concentration and then at least partially recirculated to the step (i), and where the liquid acid of the second section is at least partially removed as a product.

In another preferred embodiment, the gas purification is a drying tower, preferably a drying tower of a sulfuric acid plant. Thus, the present invention also provides a process for the production of sulfuric acid with a certain maximum concentration within a drying tower, comprising the steps of:

(i) feed a liquid acid absorber with a concentration that is greater than the (maximum) concentration of the product;

(ii) passing gas containing water through a drying tower, so that water is at least partially absorbed in the liquid acid to reduce the concentration of the liquid acid to less than the maximum concentration;

(iii) remove the liquid acid from the collector of the drying tower,

where the collector of the drying tower is divided by a dividing wall in a first and a second section, where the liquid acid collected in the first section is concentrated to a concentration that is greater than the (maximum) concentration of the product and then it is recirculated at least partially to step (i), and where the liquid acid of the second section is removed at least partially.

In particular, the concentration of the liquid acid within the sulfuric acid drying tower should be adjusted to a concentration greater than 92% by weight, preferably from 93 to 94% by weight.

The invention further comprises an installation for the production of sulfuric acid, which is suitable for performing the method according to any one of claims 1 to 5.

The installation comprises a gas purifier in the form of a packed bed absorber or a packed bed drying tower, with a liquid acid delivery system, a gas inlet and a gas purifier manifold with an acid outlet, wherein the gas purifier manifold is divided by a dividing wall into a first section and a second section, where separate outlets are arranged for the first and second section, respectively, and where the first section is connected to the system of acid contribution.

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An inlet for an adjustment liquid is provided in the first section, where a lance is provided to introduce the adjustment liquid in the first section. The concentration adjustment can also be done after the acid has been removed from the first section.

The partition wall inside the gas purifier is preferably made of brick or carbon steel or stainless steel, with or without brick cladding.

If the upper level of the dividing wall is below the lowest point of the gas inlet, it can be ensured that the gas introduced into the gas purifier does not pass through the acid collected in the gas purifier manifold, with so that no further absorption occurs in this section. In addition, the introduction of acid into the gas inlet and the corrosion of said gas inlet can be avoided.

It is preferred that an overflow be arranged between the first and second sections, in particular from the second section to the first section.

Preferably, a level control is arranged in the first section and / or the second section to avoid any acid exchange between the sections. Most preferred is a control of the second section.

In a particular preferred embodiment, the gas purifier is a packed bed absorber, where the liquid acid is introduced through an irrigation system and drilled through a packed bed. The packed bed increases the surface of the acid and, therefore, favors absorption.

In another preferred embodiment, the gas purifier is a packed bed drying tower.

The invention also comprises an installation for the production of sulfuric acid comprising a drying tower and / or an absorber with a liquid acid input system, a gas inlet for a gas and a manifold with an acid outlet, wherein The manifold is divided by a dividing wall into a first section and a second section, where separate outlets are arranged for the first and second sections, respectively, and where the first section is connected to the acid supply system.

The processes of the invention and the facilities of the invention can achieve the production of sulfuric or oleic acid of a certain minimum and / or maximum concentration in an efficient manner in terms of energy and resources. The separation of the collector from the absorber and / or the collector from the drying tower allows different concentrations of sulfuric acid or oleum fractions to be produced in a single installation.

Other embodiments, advantages and applications of the invention will also be apparent from the following description of preferred embodiments and drawings.

In the drawings:

Figure 1 schematically shows an absorber suitable for performing the method of the invention for

oil production with a certain maximum concentration;

Figure 2 shows the lower section of an absorber or a drying tower used in the process and installation of the invention;

Figure 3 is a schematic cross section along line A-A of Figure 2;

Figure 4 schematically shows the method of the invention for the production of sulfuric acid in a

absorber;

Figure 5 schematically shows the method of the invention for the production of oil in an absorber;

Figure 6 schematically shows the method of the invention for the production of sulfuric acid with a certain minimum concentration in a drying tower.

The invention is first illustrated, by way of example, with reference to Figures 1 to 3.

An absorber 1 is shown in Figure 1 as a packed bed absorption tower comprising a packed bed 2 located above a collector 3 of the absorber. Above the packed bed 2, an acid delivery system 4 is arranged in the form of an irrigation system known in the art, to introduce sulfuric acid, in particular sulfuric acid or oleum, which is then pierced through the packed bed 2 and collects in collector 3 of the absorber. A gas inlet 5 is arranged below the packed bed 2, to introduce a gas containing sulfur trioxide (SO3) and possibly containing sulfur dioxide (SO2), which then flows upstream in countercurrent flow through the packed bed 2. By contact with the descending sulfuric acid, sulfur trioxide is absorbed in the acid, thereby increasing the concentration of acid.

In the case of oil production, the non-absorbed sulfur trioxide can be recycled to the gas inlet 5 at

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through the recycling pipe 6. Alternatively, the gas containing sulfur trioxide and possibly sulfur dioxide can be derived, through the pipe 6, to the gas outlet 7, and by means of the gas valve 8 the amount of derived gas can be adjusted.

A dividing wall 9 divides the collector 3 of the absorber into a first section 3a and a second section 3b.

A diluent medium, in particular water or acid for dilution, is introduced into the first section 3a through the pipe 10 to reduce the acid concentration in said section 3a to a desired value. Using the valve 11, the amount of diluent medium can be adjusted. In case the diluent medium is sulfuric acid, the acid can be taken for dilution of a drying tower (not shown) and introduced into the absorber 1 through pipes 12 and 10. The liquid acid is removed from the first section 3a through the outlet nozzle 13 (Figure 2) and the pipes 14, 15 by the pumps 16, 17, and then recycled to the acid supply system 4 through the recycling pipe 18. The acid temperature can be adjusted by heat exchangers (chillers) 19, 20 before being recycled to the absorber 1.

Obviously, it is possible to use only one outlet nozzle 13, pipe 14, pump 16 and heat exchanger 19, respectively. Dilution can also be carried out outside the collector 3 of the absorber after removing the acid from the first section 3a.

From the second section 3b of the collector 3 of the absorber, the acid / oleic is removed as product / oleic acid through an outlet nozzle 21 (Figure 2) and the pipe 22, by means of the pump 23 and the heat exchanger 24 (cooler), and then removed through pipe 25 and / or partially recycled to second section 3b through pipe 26. The amount of recycled acid / oleum can be controlled through valve 27, controlled by the valves 28 the amount of acid / oil product extracted from the process. The concentration of the product acid / oleum is adapted to the desired value by the introduction of a diluent medium such as water or dilution acid, which is shown in Figures 4 and 5, where water (Figure 4) or acid is respectively introduced (Figure 5) in tank 29.

Figure 2 shows the bottom of the absorber 1 with the packed bed 2 (partially) and the collector 3 of the absorber. As can be seen in Figure 2, the partition wall 9 is made of brick, but it can also be made of other suitable materials, such as carbon steel, stainless steel, etc.

In the case of the counter-current flow configuration shown, the gas inlet 5 for the gas containing SO3 is located below the packed bed 2 and its lowest point is at a predetermined distance h, preferably 100-300 mm, above the upper level of the partition wall 9, in order to ensure that the gas containing SO3 does not flow through the acid product of the second section 3b.

In the first section 3a of the collector 3 of the absorber, the diluent medium is introduced, preferably through a lance 30, directly into the first section 3a. Other means can be provided for introducing the diluent medium, such as a nozzle above the acid level in the first section 3a. The diluted acid for the first section 3a is removed through the nozzle 13. The level of acid in the first section 3a is controlled in level to ensure that no dilute acid enters the second section through the dividing wall 9.

The level of liquid in the second section 3b is defined by the height of the dividing wall and the relationship between the acid that permeates the first section 3a from the packed bed 2 and the acid flow that is withdrawn through the nozzle 21 output Although the level of acid in the second section 3b can be controlled in level in a manner similar to the first section 3a, it is preferred that the second section 3b (the product section) be designed so that the amount of descending liquid is greater than the rate of production, that is, the flow of acid withdrawal through the nozzle 21. Therefore, an overflow of acid always occurs from the second section 3b to the first section 3a. The overflow may occur above the upper level of the partition wall 9 or through a specific overflow conduit (not shown). The calculation for the minimum area of the second section 3b (product section) is based on:

desired production rate (m3 / h) divided by the irrigation rate (m3 / m2 h)

In Figure 6 the production of sulfuric acid within the drying tower 31 according to the invention is shown schematically. The drying tower 31 is a drying bed with a packed bed comprising a packed bed 32 located above a drying tower collector 33.

Above the packed bed 32 is an acid delivery system (not shown), known in the art, for introducing sulfuric acid or oleum, which then perculates through the packed bed 32 and is collected in the manifold 33 of the tower of dried A gas inlet 34 is disposed below the packed bed 32 to introduce a gas that contains water, for example air, and possibly contains oxygen and sulfur dioxide (SO2), which then flows upward in countercurrent flow through the bed packaged 32 and removed through gas outlet 35. Water is absorbed by contact with the sulfuric acid that descends, thus reducing the concentration of the acid.

A dividing wall 9 divides the collector 33 of the drying tower into a first section 33a and a second section

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33b By introducing highly concentrated sulfuric acid, through the pipe 36, the diluted acid of the first section 33a is concentrated. The concentrated acid is recycled, through the pipe 37, towards the top of the drying tower. From the second section 33b dilute acid is removed through the pipe 38 and the pump 39.

Example 1 (production of sulfuric acid in the absorber)

As shown in Figure 4, liquid sulfuric acid (H2SO4) is directed from conduit 12 at a temperature of 70 to 90 ° C, preferably 80 ° C, plus cross-flow acid from the tower drying, the absorber 1 being made of stainless steel or carbon steel coated with brick. Apart from having the specified concentration and temperature, the liquid H2SO4 is virtually free of contaminating compounds such as sulfur dioxide (SO2) and nitrous oxides (NOx). The liquid H2SO4 is injected in a volume corresponding to irrigation rates between 10 and 40 m3 / m2 h and drains down through a packed bed 2 constituted by ceramic frames to the collector 3 of the absorber, and simultaneously it is passed to its through a gas containing sulfur trioxide (SO3), in countercurrent flow, through the gas inlet 5 of the absorber 1. The inlet for the gas containing SO3 is located below the packed bed 2 and above the level upper part of the partition wall 9. The gas containing SO3 enters the absorber at a temperature of 160 to 240 ° C, with a volume fraction of SO3 of 5 to 35% by weight. Due to the reaction of SO3 with the water contained in sulfuric acid, the concentration of sulfuric acid increases to 99.4% by weight. The non-absorbed SO3 leaves the absorber 1 through the pipe 7 located at the top of the absorber 1 and can optionally be recycled. Typically, the volume fraction of SO3 has been reduced to much less than 1% by weight when it exits the absorber 1.

The sulfuric acid with a concentration of 99.4% by weight and a temperature of 90 to 140 ° C is collected in the collector 3 of the absorber 1. The partition wall 9, made of acid-resistant bricks, carbon steel or stainless steel, divides the manifold 3 into two sections 3a, 3b. The liquid level in the first section 3a is controlled so that there is no liquid overflow from the first section 3a to the second section 3b. Undiluted sulfuric acid is removed from the second section 3b, through the pipe 22 and a pump 23, and is first fed to a heat exchanger 24, where it is cooled to a temperature of 70 to 90 ° C, and then to an optional diluent 29. In diluent 29 the concentration of sulfuric acid is adjusted with water to the desired final concentration of 99.1% by weight, and then removed as the final product

The sulfuric acid of the first section 3a of the collector 3 of the absorber is diluted to a concentration of 98.5% by weight through the supply of water, preferably while the concentration of the sulfuric acid is constantly monitored. The diluted sulfuric acid is removed from the absorber 1 through the pipe 14, and at least partially recycled to the absorber 1 acid supply system 4 through the conduit 18.

Example 2 (oil production)

As shown in Figure 5, it is directed in a closed loop oil (H2S2O7) liquid, with a concentration of free SO3 of 34% by weight and a temperature of 40 to 70 ° C, preferably 50 ° C, towards the part top of an absorber 1 made of carbon steel or stainless steel or carbon steel coated with brick. Liquid oil is fed to the top of the tower, and it drains down through a packed bed

2 constituted by ceramic fillings, for example Intalox mounts, towards the collector 3 of the absorber, and simultaneously it is put in contact, by countercurrent flow, with a gas containing sulfur trioxide (SO3) that is introduced into the absorber 1 a through the gas inlet 5. The inlet for the gas containing SO3 is located below the packed bed 2 and above the upper level of the partition wall 9. The gas containing SO3 enters the absorber at a temperature of 160 at 240 ° C and with a volume fraction of 5 to 35% by weight. Due to the reaction of SO3 with the acid contained in the oil, the concentration of free SO3 in the oil is increased to 35.5% by weight. The non-absorbed SO3 leaves the absorber 1 through the pipe 7 located at the top of the absorber 1, and can optionally be recycled.

In the collector 3 of the absorber 1 the oil is collected with a concentration of 35.5% by weight of free SO3 and an elevated temperature. The dividing wall 9 divides the manifold 3 into two sections 3a, 3b. The liquid level in the first section 3a is controlled so that there is no liquid overflow from the first section 3a to the second section 3b. Undiluted oil is removed from the second section 3b, through the pipe 22 and a pump 23, and is fed first to a heat exchanger 24 and then to an optional diluent 29. In the diluent 29 it is adjusted with acid the concentration of the oil to the desired final concentration of 35.1% by weight of free SO3, and is removed as the final product.

By means of the contribution, through the pipe 10, of sulfuric acid having a concentration of 98 to 99% by weight, the oil of the first section 3a of the collector is diluted to a concentration of 34% by weight of free SO3

3 of the absorber, preferably while the concentration of sulfuric acid is constantly monitored and monitored. The diluted oil is removed from the absorber 1 through the pipe 14, and is recycled at least partially towards the top of the absorber 1.

Example 3 (production of sulfuric acid in the drying tower)

As shown in Figure 6, it is directed from the drying tower 31, which is made of stainless steel or brick clad carbon steel, liquid sulfuric acid (H2SO4) with a concentration of 94% by weight and a temperature from 70 to 90 ° C, and injected in a volume corresponding to irrigation rates between 10 to 40 m3 / m2 h, and this drains down through a packed bed 32 constituted by ceramic mounts towards the collector 33 of The drying tower. At the same time, air drying, 31 as a gas containing water, is introduced into the gas drying tower 31 through the inlet 34 for gas. The gas inlet is below the packed bed 32 and above the upper level of the partition wall 9. The gas containing water enters the drying tower at a temperature of 5 to 40 ° C. Due to the hygroscopic properties of sulfuric acid, water contained in the air is absorbed in the acid, and the concentration of sulfuric acid decreases to 93% by weight.

10 Dry air 31 comes out of the drying tower, with a water content of less than 50 mg (H2O) / Nm3, through the pipe 35 located at the top of the drying tower 31, and can be used for combustion of elemental sulfur. In a further embodiment, the outlet gas of the global sulfuric acid production process is recycled to the drying tower, since this outlet gas contains unreacted sulfur dioxide.

In the collector 33 of the drying tower 31 the sulfuric acid is collected with a concentration of 93% by weight and a

15 temperature from 80 to 100 ° C. The partition wall 9 made of acid-resistant bricks, carbon steel or stainless steel, divides the manifold 33 into two sections 33a, 33b. The liquid level in the first section 33a is controlled so that there is no liquid overflow from the first section 33a to the second section 33b. Sulfuric acid is removed from the second section 33b, through the pipe 38 and a pump 39, and the final product is taken out.

The sulfuric acid of the first section 3a of the collector 3 of the absorber is concentrated to a concentration of 94% by weight, by providing sulfuric acid with a concentration of at least 98% by weight through the pipe 36, preferably while the concentration of sulfuric acid is constantly monitored. Concentrated sulfuric acid is removed from the drying pipe 31 from the drying tower 31, and at least partially recycled to the top of the drying tower 31.

25 List of reference numbers:

 1 absorber

 2 packed bed

 3 absorber manifold

 3rd section

 30

 3b second section

 4 acid delivery system

 5 gas inlet (for gas containing SO3)

 6 recycling pipe

 7 gas outlet

 35

 8 gas valve

 9 dividing wall

 10 pipe

 11 valve

 12 cross flow pipe

 40

 13 outlet nozzle

 14, 15 acid effluent pipe

 16, 17 bomb

 18 recycling pipe

 19, 20 heat exchanger

 Four. Five

 21 outlet nozzle

 22 pipe

10

fifteen

23 bomb

24 heat exchanger

25 pipe

26 pipe 27, 28 valves

29 diluent

30 spear

31 drying tower

32 packed bed of the drying tower

33 drying tower collector

34 gas inlet

35 gas outlet

36 pipe

37 recycling pipe

38 pipe

39 bomb

h distance from upper level of partition wall 9 to gas inlet 5

Claims (11)

5 10 fifteen twenty 25 30 35 40 1. A process for the production of sulfuric acid, comprising the steps of: (i) feeding liquid acid with a first concentration to a gas purification in the form of a packed bed absorber or a packed bed drying tower; (ii) passing a gas through the gas purification so that a second concentration of the liquid acid is reached; (iii) removing the liquid acid from the gas purification manifold, where the gas purification manifold is divided by a dividing wall into a first and a second section, characterized by that the concentration of the liquid acid collected in the first section is adjusted to the first concentration, at least partially the liquid acid is fed back with the first concentration from the first section to step (i), and at least partially the liquid acid with the second concentration in the second section is removed as a product, and the concentration of the liquid acid in the first section is adjusted with acid or water. 2. The method according to claim 1, characterized in that in step (ii) the gas is conducted through the purification of gas in countercurrent flow or in parallel stream flow relative to the liquid acid. 3. The method according to any of the preceding claims, characterized in that the first and / or the second section are controlled in level. 4. The method according to any of the preceding claims, characterized in that the volume of descending acid introduced in the second section is greater than the amount of product removed from the second section. 5. The process according to any of the preceding claims, characterized in that the liquid acid is sulfuric acid or oleic acid and the gas comprises SO3. 6. An installation for the production of sulfuric acid, in particular by a method according to any one of claims 1 to 5, comprising a gas purifier (1) in the form of a packed bed absorber or a packed bed drying tower which contains a supply system (4) for liquid acid, a gas inlet (5) and a gas purifier manifold (3), wherein the gas purifier manifold (3) is divided by a dividing wall (9 ) in a first section (3a) and a second section (3b), separate outputs (14, 22) are arranged for the first and second sections (3a, 3b), respectively, and the first section (3a) is connected to the acid supply system (4) through a recycling pipe (16), characterized in that in the first section (3a) an inlet for an adjustment liquid is arranged. 7. The installation according to claim 6, characterized in that a lance (30) is arranged to introduce the adjustment liquid into the first section (3a). 8. The installation according to any of claims 6 or 7, characterized in that the partition wall (9) is made of bricks or carbon steel or stainless steel. 9. The installation according to any of claims 6 to 8, characterized in that the upper level of the partition wall (9) is located below the lowest point of the gas inlet (5). 10. The installation according to any of claims 6 to 9, characterized in that an overflow is arranged between the first and second sections (3a, 3b). 11. The installation according to any of claims 6 to 10, characterized in that a level control is arranged in the first and / or second section (3a, 3b).